Power supply unit and swivel joint

Abstract

A power supply unit (50) attached to a swivel joint, the power supply unit (50) being provided with: a rotary transformer (53) connected to each of an upper swivel body and a lower traveling body of a work vehicle; an oscillation circuit (52) that is connected to the upper rotating body, converts electric power into alternating current, and supplies the alternating current to the rotary transformer; and a smoothing circuit (54) that is connected to the lower traveling body and that converts the power output from the rotary transformer (53) into direct current, the negative-side electrode of the smoothing circuit (54) being electrically connected to the housing of the lower traveling body, and the negative-side electrode of the smoothing circuit (54) being electrically connected to the housing of the lower traveling body. An electrode on the front side of the smoothing circuit (54) is taken out from the lower part of the swivel joint via a cable inserted through a duct (21) provided in the inside of the swivel joint in the axial direction.

Description

Technical Field

[0001] The invention relates to a power supply unit and a rotary joint. Background Art

[0002] For example, a rotary joint of a work vehicle such as a hydraulic excavator having an upper rotary body and a lower traveling body is provided with a plurality of hydraulic pipes that are rotatable in order to control a motor, a bulldozer, etc. Thus, the rotary joint is provided with a plurality of working oil flow paths through which high-pressure and high-speed working oil can pass. A technology using a rotary transformer is known in order to transmit power from the upper rotary body side to the lower traveling body side of the work vehicle.

[0003] Prior Art Literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 63-266292 Summary of the invention

[0006] Problems to be solved by the invention

[0007] When a rotary transformer is used to transmit electric power, the transmitted electric power is AC, so at least two cables are required inside the rotary joint. In the technology described in Patent Document 1, a cable is provided to transmit the electric power inside the rotary joint while keeping the output from the rotary transformer as AC. Therefore, a two-core cable is arranged inside the rotary joint.

[0008] However, when a hole for a cable is newly provided inside the rotary joint, the wall thickness of the rotary joint becomes thinner. As a result, the strength of the rotary joint may be reduced. In addition, when a pipe is used for internal piping of the working oil flow path of the rotary joint, the area of ​​the working oil flow path may be reduced by the pipe for piping, and the pressure loss may increase.

[0009] An object of the aspects of the present invention is to suppress a decrease in the strength of a rotary joint and to suppress a decrease in the area of ​​a hydraulic oil flow path of the rotary joint.

[0010] Means for solving problems

[0011] According to a solution of the present invention, there is provided a power supply unit for a rotary joint installed on a working vehicle, wherein the power supply unit comprises: a rotary transformer, which is respectively connected to an upper rotary body and a lower traveling body of the working vehicle; an oscillation circuit, which is connected to the upper rotary body and converts electric power into alternating current and supplies it to the rotary transformer; and a smoothing circuit, which is connected to the lower traveling body and converts electric power output from the rotary transformer into direct current, wherein an electrode on the negative side of the smoothing circuit is electrically connected to a frame of the lower traveling body, and an electrode on the positive side of the smoothing circuit is taken out from the lower part of the rotary joint via a cable inserted through a pipe arranged axially inside the rotary joint.

[0012] According to an aspect of the present invention, there is provided a rotary joint comprising: the above-mentioned power supply unit; a rotor; a shaft disposed in a hole of the rotor; and a pipe provided in an axial direction inside the shaft.

[0013] Effects of the Invention

[0014] According to the aspect of the present invention, it is possible to suppress a decrease in the strength of the rotary joint and to suppress a decrease in the area of ​​the hydraulic oil flow path of the rotary joint. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a diagram schematically showing a work vehicle according to the embodiment.

[0016] Figure 2 It is a side cross-sectional view showing a rotary joint according to an embodiment.

[0017] Figure 3 It is a side cross-sectional view showing the power supply unit according to the embodiment.

[0018] Figure 4 It is a perspective view showing a power supply unit according to the embodiment.

[0019] Figure 5 It is a schematic diagram showing a power supply unit according to the embodiment. DETAILED DESCRIPTION

[0020] Hereinafter, the embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited thereto. The constituent elements of the embodiments described below can be combined as appropriate. In addition, some constituent elements may not be used.

[0021] [Implementation Method]

[0022] <Working vehicles>

[0023] Figure 11 is a diagram schematically showing a work vehicle according to an embodiment. The work vehicle MV includes a lower traveling body 100, an upper slewing body 200, a rotation mechanism 300, and a slewing joint 1. The upper slewing body 200 is rotatably supported by the lower traveling body 100. The work vehicle MV is a work vehicle including the upper slewing body 200 and the lower traveling body 100, such as a hydraulic excavator.

[0024] The lower traveling structure 100 and the upper revolving structure 200 are connected via a revolving mechanism 300 and a revolving joint 1. The revolving mechanism 300 and the revolving joint 1 allow the upper revolving structure 200 to revolve around the revolving axis AX with respect to the lower traveling structure 100.

[0025] The upper slewing body 200 is provided with a hydraulic pump 202 and a hydraulic oil tank 203. The lower traveling body 100 is provided with a hydraulic motor 102. The hydraulic pump 202 is connected to the slewing joint 1 via a conduit 201. The slewing joint 1 is connected to the hydraulic motor 102 via a conduit 101. The hydraulic oil tank 203 contains hydraulic oil. The hydraulic oil contained in the hydraulic oil tank 203 is supplied to the hydraulic pump 202 via an oil passage 204. The hydraulic pump 202 discharges the hydraulic oil supplied from the hydraulic oil tank 203. The hydraulic oil discharged from the hydraulic pump 202 is supplied to the hydraulic motor 102 via the conduit 201, the oil passage 30 provided in the slewing joint 1, and the conduit 101. The hydraulic oil discharged from the hydraulic pump 202 is supplied to the hydraulic motor 102, and the hydraulic motor 102 is driven, whereby the lower traveling body 100 travels. The hydraulic oil sent from the hydraulic motor 102 is returned to the hydraulic oil tank 203 via an oil passage not shown.

[0026] The rotating mechanism 300 connects the lower traveling body 100 and the upper rotating body 200. The rotating mechanism 300 has an inner ring member 301 and an outer ring member 302. The outer ring member 302 is arranged around the inner ring member 301. The inner ring member 301 and the outer ring member 302 rotate relative to each other around the rotating axis AX. The inner ring member 301 is fixed to the lower traveling body 100. The outer ring member 302 is fixed to the upper rotating body 200.

[0027] <Rotary joint>

[0028] Figure 2 1 is a side sectional view of a rotary joint according to an embodiment. The rotary joint 1 connects a lower traveling body 100 and an upper rotating body 200. The rotary joint 1 has a rotor 10 and a shaft 20 rotatably supported on the rotor 10. The rotor 10 and the shaft 20 rotate relative to each other about a rotating axis AX. The rotor 10 is fixed to the lower traveling body 100. The shaft 20 is fixed to the upper rotating body 200. Alternatively, the rotor 10 is fixed to the upper rotating body 200, and the shaft 20 is fixed to the lower traveling body 100.

[0029] A working oil flow path 22 penetrating in the axial direction is provided inside the shaft 20 of the rotary joint 1. A pipe 21 is arranged inside the working oil flow path 22. The space between the working oil flow path 22 and the pipe 21 can also be used as the flow path of the working oil. In the embodiment, the working oil is connected to a discharge circuit returning from the hydraulic motor 102 to the working oil tank 203. The pipe 21 is formed in a hollow tubular shape. The pipe 21 is formed of a conductive material such as a metal material. A cable that supplies power from the power supply unit 50 of the power supply system 5 to the lower traveling body 100 is inserted through the pipe 21. The pipe 21 is connected to the lower part 11 of the rotor 10 of the rotary joint 1 in a state where the lower end of the pipe 21 is opened. The cable inserted in the pipe 21 is taken out from the lower end of the pipe 21. The taken out cable supplies power to the lower traveling body 100.

[0030] <Power supply system>

[0031] Figure 3 It is a side cross-sectional view showing the power supply unit according to the embodiment. Figure 4 It is a perspective view showing a power supply unit according to the embodiment. Figure 5 The power supply system 5 supplies electric power to the lower traveling body 100 . The power supply system 5 includes a non-contact power supply unit (hereinafter referred to as “power supply unit”) 50 and a sensor IF (Interface) controller (hereinafter referred to as “controller”) 60 .

[0032] <Power supply unit>

[0033] The power supply unit 50 supplies power from the upper slewing body 200 to the lower traveling body 100 in a non-contact manner. The power supply unit 50 is mounted on the upper part of the slewing joint 1. The power supply unit 50 includes a DC / DC converter 51, an oscillation circuit 52, a rotary transformer 53, a smoothing circuit 54, and a rotation sensor 55.

[0034] The DC / DC converter 51 outputs the power supplied from the upper rotating body 200 side to the oscillation circuit 52. The DC / DC converter 51 converts the supplied 24 [V] direct current into 5 [V] direct current and outputs it. In the embodiment, the DC / DC converter 51 is arranged on the oscillation circuit substrate arranged above the rotation sensor 55. In the embodiment, the DC / DC converter 51 is arranged on the upper part of the main body 591. In the embodiment, the DC / DC converter 51 is arranged at a position above the rotation sensor 55 and the magnet part 56.

[0035] The oscillation circuit 52 is connected to the upper rotating body 200, converts the power into AC and supplies it to the rotary transformer 53. The oscillation circuit 52 converts the DC supplied from the DC / DC converter 51 into a high-frequency AC. The oscillation circuit 52 outputs the AC to the rotary transformer 53. In the embodiment, the oscillation circuit 52 is arranged on an oscillation circuit substrate arranged above the rotation sensor 55. In the embodiment, the oscillation circuit 52 is arranged on the upper part of the main body 591. In the embodiment, the oscillation circuit 52 is arranged above the rotation sensor 55 and the magnet part 56.

[0036] The rotary transformer 53 is connected to the upper rotating body 200 and the lower traveling body 100, respectively. The rotary transformer 53 is arranged coaxially with the rotating shaft AX of the rotary joint 1. The central portion of the rotary transformer 53 is hollow, and the shaft portion, that is, the small diameter portion, of the rotating shaft 592 coaxial with the rotating shaft AX of the rotary joint 1 is inserted therethrough. In the embodiment, the rotary transformer 53 is arranged below the oscillation circuit 52. In the embodiment, the rotary transformer 53 is arranged below the rotation sensor 55 and the magnet portion 56. In the embodiment, the rotary transformer 53 is arranged above the smoothing circuit 54. In the embodiment, the upper portion of the rotary transformer 53 is arranged on the main body 591 fixed to the upper rotating body 200 side. In the embodiment, the upper portion of the rotary transformer 53 protrudes upward more than the large diameter portion of the rotating shaft 592. In the embodiment, the lower portion of the rotary transformer 53 is arranged on the large diameter portion of the rotating shaft 592. In the embodiment, when the rotary joint 1 rotates around the rotation axis AX, the lower portion of the resolver 53 rotates together with the rotation axis 592 .

[0037] The smoothing circuit 54 is connected to the lower traveling body 100, and converts the AC supplied from the rotary transformer 53 into a DC. The smoothing circuit 54 supplies a DC of about 10 [V] or more and 15 [V] or less to the lower traveling body 100. In the embodiment, the smoothing circuit 54 is arranged at a position on a smoothing circuit substrate arranged below the rotary transformer 53. In the embodiment, the smoothing circuit 54 is arranged above the spring 545. In the embodiment, the smoothing circuit 54 is arranged above the pipe 21 provided inside the mounting shaft 595 and the shaft 20 of the rotary joint 1.

[0038] The negative electrode of the smoothing circuit 54 is electrically connected to the frame of the lower traveling body 100. The positive electrode of the smoothing circuit 54 is taken out from the lower part of the rotary joint 1 via a cable inserted through a pipe 21 provided in the rotary joint 1 along the axial direction.

[0039] The mounting plate 542 , the mounting plate 544 , the spring 545 , the crimping terminal 546 , and the spring 547 are formed of a conductive material such as a metal material.

[0040] The mounting plate 542 is axially arranged above the mounting plate 544. The mounting plate 544 is axially arranged below the mounting plate 542. The mounting plate 542 and the mounting plate 544 are axially separated and arranged opposite to each other. The mounting plate 542 and the mounting plate 544 sandwich the spring 545 in the axial direction. The mounting plate 542, the mounting plate 544, and the spring 545 are electrically connected.

[0041] The spring 545 is electrically connected to the positive electrode of the smoothing circuit 54 to transmit a positive voltage. The spring 545 is electrically connected to the mounting plate 542, the mounting plate 544, and the crimping terminal 546. In the embodiment, the spring 545 is clamped by the mounting plate 542 and the mounting plate 544. In the embodiment, the spring 545 is arranged below the smoothing circuit substrate on which the smoothing circuit 54 is arranged. In the embodiment, the spring 545 is arranged above the pipe 21 provided inside the mounting shaft 595 and the shaft 20 of the rotary joint 1.

[0042] The spring 545 is attached to the rotating shaft 592 and the mounting shaft 595 in a state of being sandwiched between the mounting plate 542 and the mounting plate 544 in the axial direction.

[0043] The crimping terminal 546 is an electrode on the positive side of the smoothing circuit 54. The crimping terminal 546 is fixed to the mounting plate 544. The crimping terminal 546 is electrically connected to the mounting plate 544. The crimping terminal 546 is electrically connected to a cable inserted into the pipe 21 provided inside the shaft 20 of the rotary joint 1. The surface of the cable is covered with an insulating material. In the embodiment, the crimping terminal 546 is arranged in the middle of the mounting plate 542 and the mounting plate 544.

[0044] The spring 547 is electrically connected to the negative electrode of the smoothing circuit 54, and transmits a negative voltage (ground voltage). The spring 547 is fixed to the outer peripheral surface of the rotating shaft 592 and the outer peripheral surface of the mounting shaft 595. The spring 547 is electrically connected to the rotating shaft 592 and the mounting shaft 595. In the embodiment, the spring 547 is arranged below the smoothing circuit substrate on which the smoothing circuit 54 is arranged. In the embodiment, the spring 547 is arranged above the pipe 21 provided inside the mounting shaft 595 and the shaft 20 of the rotary joint 1.

[0045] The mounting plate 542 is fixed to a copper foil portion (not shown) exposed on the lower surface of the smoothing circuit substrate on which the smoothing circuit 54 is arranged by a resin screw (not shown). As a result, the copper foil portion on the lower surface of the smoothing circuit substrate contacts and is electrically connected to the mounting plate 542. The power from the smoothing circuit 54 flows through the mounting plate 542, the spring 545, and the crimping terminal 546 to the cable inserted into the pipe 21 provided inside the shaft 20 of the rotary joint 1.

[0046] The insulating portion 541 and the insulating portion 543 are formed of a glass epoxy material. The insulating portion 541 and the insulating portion 543 are disposed opposite to each other in an axial direction and separated from each other. The insulating portion 541 is disposed in a state where the surface is in contact with the upper surface of the mounting plate 542. The insulating portion 543 is disposed in a state where the surface is in contact with the lower surface of the mounting plate 544. The insulating portion 541 and the insulating portion 543 clamp the mounting plate 542, the mounting plate 544, the spring 545, and the crimping terminal 546 in the axial direction. The insulating portion 541 electrically insulates the smoothing circuit 54 from the mounting plate 542, the spring 545, and the crimping terminal 546. The insulating portion 543 electrically insulates the mounting plate 544, the spring 545, and the crimping terminal 546 from the mounting shaft 595.

[0047] The rotation sensor 55 is a sensor for detecting the rotation angle of the rotation axis AX of the rotary joint 1. In the embodiment, the rotation sensor 55 is arranged below the oscillation circuit 52 and above the rotary transformer 53. The rotation sensor 55 is arranged above the pipe 21 provided inside the shaft 20 of the rotary joint 1. The rotation sensor 55 is arranged coaxially with the rotation axis AX of the rotary joint 1. The rotation sensor 55 is arranged at the upper end of the rotation axis 592 arranged coaxially via the mounting shaft 595 on the upper part of the shaft 20 of the rotary joint 1. The rotation sensor 55 receives power from the main controller arranged on the upper rotating body 200 through the cable, and outputs sensor data to the main controller through the cable. The rotation sensor 55 has a magnet part 56. The magnet part 56 is arranged at the upper end of the rotation axis 592. The magnet part 56 rotates with the shaft 20 of the rotary joint 1 around the rotation axis AX. The relative rotation angle between the magnet part 56 and the rotation sensor 55 is detected by the Hall element of the rotation sensor 55.

[0048] The main body 591 , the rotating shaft 592 , the bushing 593 a , the bushing 593 b , the cover 594 , and the mounting shaft 595 are formed of a conductive material such as a metal material.

[0049] The main body 591 and the cover 594 define the outer shape of the power supply unit 50. The main body 591 is formed in a cylindrical shape. The DC / DC converter 51, the oscillation circuit 52, the rotary transformer 53, the smoothing circuit 54, and the rotation sensor 55 are accommodated inside the main body 591. The rotating shaft 592 and the mounting shaft 595 are arranged inside the main body 591.

[0050] The rotating shaft 592 is arranged inside the main body 591. The rotating shaft 592 is arranged on the upper part of the shaft 20 of the rotary joint 1 coaxially with the rotating axis AX via the mounting shaft 595. The rotating shaft 592 rotates together with the shaft 20 of the rotary joint 1 around the rotating axis AX. The rotating shaft 592 is integrally formed with a large diameter portion and a small diameter portion along the axial direction. The large diameter portion of the rotating shaft 592 is arranged below in the axial direction. The lower part of the rotary transformer 53 and the smoothing circuit 54 are arranged at the large diameter portion of the rotating shaft 592. The small diameter portion of the rotating shaft 592 is an axial portion coaxial with the rotating axis AX of the rotary joint 1. The small diameter portion of the rotating shaft 592 is arranged above in the axial direction. The rotary transformer 53 is arranged at the small diameter portion of the rotating shaft 592.

[0051] The rotating shaft 592 is fixed to the smoothing circuit substrate on which the smoothing circuit 54 is arranged by screws. The rotating shaft 592 is fixed to the copper foil portion (not shown) exposed on the upper surface of the smoothing circuit substrate by a resin screw (not shown). As a result, the copper foil portion on the upper surface of the smoothing circuit substrate contacts and is electrically connected to the rotating shaft 592.

[0052] The bushing 593a and the bushing 593b are formed of a metal material. The bushing 593a is formed into a disk shape by a plate. The bushing 593a is between the main body 591 and the upper part of the rotating shaft 592. The bushing 593a is configured to cover the upper surface of the large diameter part of the rotating shaft 592. The bushing 593b is formed into a cylindrical shape by a plate. The bushing 593b is between the main body 591 and the radial outer side of the rotating shaft 592. The bushing 593a is configured to cover the radial outer side of the rotating shaft 592 of the rotating shaft 592. The bushing 593a and the bushing 593b are electrically connected to the main body 591 and the rotating shaft 592.

[0053] The cover 594 defines the outer shape of the power supply unit 50 together with the main body 591. The cover 594 is disposed on the upper portion of the main body 591.

[0054] The mounting shaft 595 is a shaft for mounting the power supply unit 50 on the pipe 21 provided inside the shaft 20 of the rotary joint 1. The mounting shaft 595 mounts the power supply unit 50 on the upper portion of the pipe 21 provided inside the shaft 20 of the rotary joint 1. The mounting shaft 595 is arranged below the rotating shaft 592.

[0055] <Controller>

[0056] The controller 60 is disposed on the lower traveling body 100. The controller 60 is a working device controller that controls various functions of the lower traveling body 100 of the work vehicle MV. The controller 60 includes a power supply circuit 61, a general-purpose microcomputer (MCU: Micro Controller Unit) 62, a power supply output for a sensor 63, a general-purpose analog IF 64, a switching circuit 65, a general-purpose digital IF 66, a CAN (Controller Area Network) driver 67, a sensor 68, and a wireless chip 69. The structure of the controller 60 is an example and is not limited thereto.

[0057] The power supply circuit 61 is supplied with a direct current of about 10 [V] or more and 15 [V] or less from the smoothing circuit 54 of the power supply unit 50 . The power supply circuit 61 supplies power to each part of the controller 60 .

[0058] The MCU 62 is a general-purpose microcontroller. The MCU 62 is connected to the general-purpose analog IF 64 and the general-purpose digital IF 66 so as to be able to perform data communication. In the embodiment, the general-purpose analog IF 64 and the general-purpose digital IF 66 have a plurality of channels.

[0059] The sensor power supply output 63 outputs a direct current of about 5 [V] to the sensor 68 and the like disposed on the lower traveling body 100 .

[0060] The CAN driver 67 is a driver for performing data communication with sensors disposed on the lower traveling structure 100 via the CAN.

[0061] The sensor 68 is various sensors disposed on the lower traveling structure 100. The sensor 68 is, for example, a sensor that detects abnormality of the lower traveling structure 100. The sensor 68 is, for example, a sensor that detects vibration of the lower traveling structure 100.

[0062] The wireless chip 69 performs data communication according to a wireless standard such as ZigBee (registered trademark) or TWELITE (registered trademark). In the embodiment, the wireless chip 69 wirelessly outputs sensor data to a main controller disposed on the upper swing body 200 .

[0063] <Function>

[0064] use Figure 4 The operation of the power supply unit 50 configured in this manner, specifically, the flow path of the electric power supplied from the power supply unit 50 to the lower traveling structure 100 will be described.

[0065] The current flow path A1 is a positive voltage current flow path in the smoothing circuit 54. The current flow path A1 is a positive voltage current flow path taken out from the smoothing circuit 54 through the mounting plate 542, the spring 545, the crimping terminal 546, and the cable from the lower portion 11 of the rotary joint 1.

[0066] The current flow path A2 is a current flow path of a negative voltage in the smoothing circuit 54. The current flow path A2 is a flow path of a negative voltage current that flows to the smoothing circuit 54 via the pipe 21 of the rotary joint 1, the mounting shaft 595, the spring 547, and the rotating shaft 592.

[0067] The current flow path A3 is another current flow path of the negative voltage in the smoothing circuit 54. The current flow path A3 is a flow path of the negative voltage current flowing to the smoothing circuit 54 via the rotary joint 1, the main body 591, the bushing 593a, the bushing 593b, and the rotating shaft 592.

[0068] <Effect>

[0069] As described above, according to the embodiment, the negative electrode of the smoothing circuit 54 is electrically connected to the frame of the lower traveling body 100. According to the embodiment, the positive electrode of the smoothing circuit 54 is taken out from the lower part 11 of the rotary joint 1 via the cable inserted into the pipe 21 provided along the axial direction inside the rotary joint 1. Therefore, according to the embodiment, a single-core cable may be arranged inside the rotary joint 1. For example, when a hole for the cable is newly provided inside the rotary joint 1, the cross-sectional area occupied by the cable can be reduced compared with the case of two cores. According to the embodiment, the influence on the wall thickness of the working oil flow path 22 of the rotary joint 1 can be reduced, and the reduction in the strength of the rotary joint 1 can be suppressed to the minimum. Specifically, if the diameter of the two-core cable is set to Φ2d, the diameter of the single-core cable is less than Φd, and the cross-sectional area is 1 / 4 times. According to the embodiment, the number of cores of the cable can be reduced. According to the embodiment, a rotary joint 1 with a smaller size and low cost can be provided. In this way, the embodiment can suppress a decrease in the area of ​​the hydraulic oil flow path 22 of the rotary joint 1 and suppress an increase in pressure loss to a minimum. The embodiment can suppress a decrease in the strength of the rotary joint 1.

[0070] In the embodiment, the rotary transformer 53 can be arranged coaxially with the rotation axis AX of the rotary joint 1. In the embodiment, the rotary transformer 53 can be arranged at an appropriate position.

[0071] In the embodiment, a rotation sensor 55 that detects the rotation of the rotary joint 1 can be arranged. In the embodiment, the rotation of the rotary joint 1 can be detected while transmitting electric power to the lower traveling body 100.

[0072] In the embodiment, the rotation sensor 55 can be arranged coaxially with the rotation axis AX of the rotary joint 1. In the embodiment, the rotation sensor 55 can be arranged at an appropriate position.

[0073] In the embodiment, the smoothing circuit 54 can be arranged below the rotary transformer 53. In the embodiment, the smoothing circuit 54 can be arranged at an appropriate position. According to the present embodiment, electric power can be supplied to the lower traveling body 100 side through a single-core cable.

[0074] In the embodiment, the rotary transformer 53 can be arranged below the oscillation circuit 52. In the embodiment, the rotary transformer 53 can be arranged at an appropriate position.

[0075] In the embodiment, the rotation sensor 55 can be arranged below the oscillation circuit 52 and above the resolver 53. In the embodiment, the rotation sensor 55 can be arranged at an appropriate position.

[0076] <Modification>

[0077] The arrangement of the rotary transformer 53 and the rotation sensor 55 in the power supply unit 50 is not limited to the above. The rotary transformer 53 may be arranged above the rotation sensor 55 .

[0078] Description of Reference Numerals

[0079] 1…rotary joint; 5…power supply system; 10…rotor; 20…shaft; 21…pipe; 22…operating oil flow path; 30…oil path; 50…contactless power supply unit (power supply unit); 51…DC / DC converter; 52…oscillation circuit; 53…rotary transformer; 54…smoothing circuit; 55…rotation sensor; 56…magnet unit; 60…sensor IF controller (controller); 61…power supply circuit; 62…general-purpose microcomputer (MCU); 63…power supply output for sensor; 64…general-purpose analog IF; 65…switching circuit; 66…general-purpose digital IF; 67…CAN driver; 68…sensor; 69… Wireless chip; 100…lower traveling body; 101…duct; 102…hydraulic motor; 200…upper rotating body; 201…duct; 202…hydraulic pump; 203…working oil tank; 204…oil circuit; 300…rotating mechanism; 301…inner ring member; 302…outer ring member; 541…insulating portion; 542…mounting plate; 543…insulating portion; 544…mounting plate; 545…spring; 546…crimping terminal; 547…spring; 591…main body; 592…rotating shaft; 593a…bushing; 593b…bushing; 594…cover; 595…mounting shaft; AX…rotating shaft; MV…working vehicle.

Claims

1. A power supply unit, which is a power supply unit installed on a swivel joint of a working vehicle, wherein: The power supply unit comprises: A rotary transformer, which is respectively connected to the upper rotating body and the lower traveling body of the working vehicle; an oscillation circuit connected to the upper rotating body and converting electric power into alternating current to supply the electric power to the rotary transformer; and a smoothing circuit connected to the lower traveling body and converting the electric power output from the rotary transformer into direct current, The negative electrode of the smoothing circuit is electrically connected to the frame of the lower traveling body. The positive electrode of the smoothing circuit is taken out from the lower portion of the rotary joint via a cable inserted through a pipe provided along the axial direction inside the rotary joint.

2. The power supply unit according to claim 1, wherein: The rotary transformer and the rotary joint have rotating shafts coaxially disposed.

3. The power supply unit according to claim 1, wherein: The power supply unit further includes a rotation sensor that detects rotation of the rotary joint.

4. The power supply unit according to claim 3, wherein: The rotation sensor and the rotation axis of the rotary joint are coaxially arranged.

5. The power supply unit according to claim 1, wherein: The smoothing circuit is arranged below the resolver.

6. The power supply unit according to claim 5, wherein: The rotary transformer is arranged below the oscillation circuit.

7. The power supply unit according to claim 4, wherein: The rotation sensor is arranged below the oscillation circuit and above the resolver.

8. A swivel joint, wherein: The rotary joint has: The power supply unit according to any one of claims 1 to 7; Rotor; a shaft disposed in the hole of the rotor; and The hydraulic oil flow path is provided in the interior of the shaft along the axial direction.

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